Ratios

Rate

Proportions

**Ratios, Rates, and**

Proportions Oh My!

Proportions Oh My!

For every 4 girls in my class there are 3 boys...

Grapes at Sunflower are $1.29 a lb

And Old Navy has a black Friday deal where for every 2 pairs of jeans you buy, you will get 1 pair free!

What do these things all have in common?

By the end of this, you will know!

...and earn extra credit!

A ratio is a comparison of two quantities (amounts) with the same unit of measure.

There are 3 TYPES of ratios:

part to part

part to whole

whole to part

There are 3 WAYS TO WRITE ratios:

as a fraction 2/3

using a colon 2 snickers : 3 butterfingers

using the word "to" 2 snickers to 3 butterfingers

A rate is a comparison of two quantities with DIFFERENT units of measurement.

When you have two ratios that are equivalent.

Sound familiar...?

That's because proportions are just like equivalent fractions!

http://www.youtube.com/watch?v=vdl-yKCdkyU

Lets take a moment and create ratios to represent the students in a class. Webmail your responses to your math teacher for extra credit.

Suppose that there are 17 girls, 19 boys, and 1 teacher. What are the following ratios?

girls to boys

girls to students

students to boys

teacher to students

Unit Rate

This is a special kind of rate where the second quantity is 1. The denominator in your fraction is 1.

how fast did we just move???? Speed is a rate

...like mph which stands for

miles per hour.

That means miles per 1 hour

Can you think of any other examples of unit rate?? Please webmail your math teacher some examples for some extra credit.

Stuck? The following video may give you some ideas.

The ratio of students who wear Toms to students who wear Converse at ColoCA is 2: 5. If 200 students at ColoCA wear Converse how many students wear Toms?

You can solve this question by setting up a proportion:

Converse

Toms

5

2

200

?

then use what you already about

equivalent fractions to solve! ...or, cross-multiply!

Converse

Toms

5

2

200

80

x 40

x 40

80 students wear Toms

Now you try...

Catherine is baking cookies. She can make a batch of 8 cookies in 30 minutes. How many cookies can she make in 5 hours?

Webmail your math teacher your response for extra credit.

Oh My!

It looks like you've learned something about ratios, rates and proportions. Maybe now you can tell me what those things mentioned in the beginning have in common. Webmail your answers to those questions, with all the other responses you've completed, to your math teacher!

equivalent fractions:

...or, cross-multiply:

2(200)

=

5x

...multiply along the diagonals

400=5x ...simplify

400/5=x ...divide by 5

80=x ...simplify

80 students wear Toms ...state your answer

5

2

200

x